Modern mobile communication devices, such as smart phones and the like, utilize various forms of acoustic devices, such as receivers (i.e., speakers) and microphones. Receivers may emit sound into a user's ear when the device is being used, such as during a phone call. Microphones may be used to receive voice input from a user during a call, the voice input being transmitted to a communication device operated by the other user on the call. Microphones may also receive sound emitted from receivers and/or sounds emitted external to the device (e.g., background noise). In certain situations, the background noise may be too loud, thereby hindering a user's ability to clearly hear the sound emitted from the receiver. Additionally, contours of a user's ear may create variation in the strength of sounds emitted from the receiver, thus causing the emitted sounds to sound muffled when the device is placed in certain positions against the user's ear.
Modern mobile communication devices may incorporate active noise cancellation and auto loudness functionalities at the receiver to address such issues. To perform active noise cancellation, a microphone may be placed in a position to receive background noise. Once the background noise is received, the receiver may emit noise-canceling sounds that induce destructive interference to cancel out the background noise. An error-detecting microphone may be placed near a receiver to measure the strength of the noise-canceling sounds emitted from the receiver. Depending on the measured strength of noise-canceling sounds, the receiver may be driven to increase or decrease the strength of its outputted sound to achieve a target active noise cancellation. In addition to achieving a target active noise cancellation, the error-detecting microphone may also be used to equalize the sound emitted from the receiver. For example, if the receiver is placed against a user's ear such that the sound is muffled, the error-detecting microphone may detect the muffled sound and cause the device to emit a stronger sound from the receiver.
Implementation of an error-detecting microphone in modern mobile communication devices may prove problematic. For example, coupling may occur between the receiver and the error-detecting microphone that adversely affects execution of active noise cancellation and/or equalization. Thus, improvements to such functionalities are desired.